Field of Invention
The present invention relates to an integrated circuit (IC) fabrication, and particularly to a scanner routing method for particle removal.
Description of Related Art
Lithography is one of the most important techniques utilized in semiconductor manufacture. Among various lithography techniques, the immersion lithography technique has been well developed to cope with the miniaturization of IC devices accompanying with the increase in degree of IC integration. An immersion lithography process is conducted in a liquid-phase environment, and has a higher resolution because the refractive index of a liquid is closer to that of the photoresist material as compared with air. Therefore, the dimensions of IC devices can be reduced with the immersion lithography technique.
However, since the photoresist layer directly contacts with the immersion liquid during the exposure step of an immersion lithography process, the immersion liquid is easily contaminated by the chemicals out-diffusing from the photoresist layer. Such contaminated immersion liquid may also diffuse into the photoresist layer and alter the properties of the latter. Therefore, the critical dimension and the uniformity of the photoresist patterns are adversely affected. Accordingly, high attention is drawn to how to remove unnecessary particles or chemicals in the immersion liquid.